[U-Boot-Users] Download of kernel Image through Serial Line.

Wolfgang Grandegger wolfgang.grandegger at bluewin.ch
Thu Jan 30 15:38:26 CET 2003

On 01/30/2003 03:44 AM leeyang wrote:
>> >- Minimum Flash Size if I don't use NFS ( full embeded application )
>> 4MB. For a resonable 'standard' Embedded Linux runtime 
>> environment for PowerPC including basic network support 
>> you need approx. the following space in Flash:
>>  U-Boot                   : 120 KB
>>  Linux kernel             : 600 KB
>>  RAMDisk image            : 1   MB
>>  Root file-system on JFFS2: 2.5 MB
> My embedded fs are 
> ppcboot+kernel+ramdisk(rootfs),However
> ramdisk will take 4.5M ram.
> I am going to switch to jffs2,
> but could you tell me the function of
> your 1M ramdisk?

The size is for a RAMdisk image built with SELF, our "Simple Embedded
Linux Framework" (see ftp://ftp.denx.de/pub/LinuxPPC/usr/src/SELF). The
size of the root filesystem is approx. 2.5MB resulting in a compressed
RAMdisk image of 1MB. You may want to put this root filesystem on a
JFFS2 or better CRAMFS partition but usually there is no real benefit.
Actually you waste flash memory space for saving little RAM space.

> Would you please check
> http://lists.infradead.org/pipermail/linux-mtd/2003-January/006836.html
> and I state my situation there.

About flash partitioning: You can define a static partition table in the
Linux kernel e.g. drivers/mtd/maps/tqm8xxl.c for the TQM8xxL modules.
With the DENX kernel you can also define the partitioning via Linux
bootargs if the kernel option CONFIG_MTD_CMDLINE_PARTS is defined. See
http://www.denx.de/doc/TQM8xxL/dplg.html#FLASH-FILESYSTEMS for further

Good luck,


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